Enhancement in thermal performance of solar dryer through conduction mode for drying of agricultural produces

This paper presents the development and performance analysis of a solar conduction dryer (SCD) used for dry-ing agricultural produce. Compared with other conventional solar dryers, which are mostly based on convection mode, it was found to be more efficient in terms of thermal efficiency, drying time, and drying rate. In addition to increasing the dryer's aperture area, reflectors were placed on both sides, which enhanced its thermal perfor-mance. Furthermore, reflectors can also be used as a closing cover to enhance the life of the covering material against rainstorms, hailstones, etc., when the dryer will not be used. The maximum temperature inside the dryer was 77.4 degrees C and 61.2 degrees C with and without the use of reflectors during no load conditions, while maximum tem-peratures inside the dryer with and without the use of reflectors measured 59.1 degrees C and 51.8 degrees C respectively during full load conditions. With and without reflectors, the drying efficiency of the developed solar dryer was found to be 59.4% and 50.09% respectively, which are much higher than that of other general solar dryers ( similar to 35%). How-ever, the drying rate varied between 1.525 to 0.005 g of water evaporated per gram of dry matter per hour when reflectors were used and 1.397 to 0.005 g without reflectors. A cost analysis showed that the capital invested for the development of SCD could be recovered in 1.02 years.